Low-spurious fractional N-frequency divider and method of use

Abstract

A fractional N-frequency divider having a reduced fractional spurious output signal, which utilizes a multi-modulus frequency divider and an accumulator to generate a calibration-timing window that is used to calibrate two oscillator circuits and a phase compensation circuit. The calibrated phase compensation circuit is then used to mitigate the fractional spurs in the output signal of the fractional N-frequency divider. The fractional N-frequency divider may be implemented into a fractional N-frequency synthesizer.

Description

FIELD OF THE INVENTION[0001]Embodiments of the present invention relate generally to frequency synthesizers, and more particularly to mitigating fractional spurs in a fractional N-frequency divider for use in a fractional N-frequency synthesizer.BACKGROUND OF THE INVENTION[0002]In many modern electronic systems, it is necessary to generate multiple output signals at various output frequencies, from one single frequency reference signal. To achieve the desired frequency resolution for modern electronic systems, fractional N-frequency synthesizers are used. In fractional-N frequency synthesizers, a fractional N-frequency divider and associated circuitry are used to establish a division ratio having a fractional component by periodically changing the division ratio of the divider, so that an average value of the output frequency contains a fractional element.[0003]It is known in the art that the use of fractional N-frequency dividers results in undesirable fractional spurs in the outpu...

AI Technical Summary

Benefits of technology

The present invention provides a system and method for mitigating fractional spurious signals in the output signal of a fractional N-frequency divider. This is achieved by generating a calibration time window and adjusting the periods of the first and second oscillator circuits to calibrate the phase compensation circuit. The calibration control word is calculated for each accumulator control word to adjust the phase compensation circuit for reducing the fraational spurious signals in the output signal. The technical effect of this invention is to provide necessary mitigation of the fractional spurs of the output signal of the fractional N-frequency divider.

Problems solved by technology

It is known in the art that the use of fractional N-frequency dividers results in undesirable fractional spurs in the output signal of the fractional N-frequency divider.

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